Means for feeding a grinding wheel of aperipheral grinding attachment into a workpiece



Dec. 18, 1956 o. BRETSCHER 2,774,197

MEANS FOR FEEDING A GRINDING WHEEL OF A PERIPHERAL GRINDING ATTACHMENT INTO A WORKPIECE Filed Aug. 9, 1954 2 Sheets-Sheet 1 INVENTOR. 0770 BRETJ'Cf/ffi WQQ Dec. 18, 1956 o. BRETSCHER 2,774,197

MEANS FOR FEEDING A GRINDING WHEEL OF A PERIPHERAL GRINDING ATTACHMENT INTO A WORKP-IEZCE Filed Aug. 9, 1954 2. Sheets-Sheet 2 rates MEANS FOR FEEDING A GRINDING WHEEL OF A PERIPHERAL GRINDING ATTACHIVIENT INTO A WORKPIECE Otto Bretscher, Gerlafingen, Switzerland, assignor to Gesellschaft der Ludw. von Rollschen Eisenwerke AG Gerlafingen, Switzerland, :1 Swiss company Unite The present invention relates to grinding wheel attachments, and in particular to means for feeding in toward a workpiece the grinding wheel of a peripheral grinding attachment.

In known grinding attachments of this type the grinding wheel shaft is supported in a vertical rest which has to be guided without play in slide bars. It is obvious that the setting of such a rest to an accuracy of a hundredth of a millimetre is diflicult since, owing to inertia and friction, tensions arise, to overcome which far greater power is required than would be necessary to displace the rest, with the result that too great a feed is easily produced.

The present invention aims at eliminating this drawback in order to enable the grinding wheel to be smoothly fed in and the grinding to be slowed down, as well as to achieve an extremely accurate and clean ground surface.

The procedure according to the invention consists in the fact that the grinding wheel is fed in a circular arc into the work piece in such a way that, the travel of the grinding wheel axis being uniform, the feed travel of the grinding wheel is, in accordance with the sine function, reduced to zero and the nominal dimension attained in this zero position.

This procedure is carried out with the aid of an attachment which is characterized by the fact that on a horizontally adjustable slide there is suspended after the fashion of a pendulum a swivel member on which is arranged a vertically adjustable grinding wheel bean'ng, the grinding wheel spindle of which is mounted parallel to the suspension arbor, means to move the swivel member being provided, and that furthermore articulated or flexibly attached to the swivel member is an arm, on the end of which a compound slide rest with a diamond dresser is secured, which in its operative position is shiftable in the plane including both said spindle and said arbor.

These and other objects of the invention will become further apparent from the following detailed description, reference being made to the accompanying drawings showing preferred embodiments of the invention.

In the drawings:

Fig. 1 is a cross-section taken along the line l-I in Fig. 2 and through the grinding attachment constructed in accordance with the present invention.

Fig. 2 is a front view of said grinding attachment,

Fig. 3 is a side view of the swivel plate and grinding wheel slide employed in said attachment,

Fig. 4 is a section along line IV-IV in Fig. 2,

Fig. 5 is a section along line VV in Fig. 2,

Fig. 6 shows an alternative embodiment of the compound slide rest to which the diamond dresser is secured, and

Fig. 7 shows still another alternative embodiment of the compound slide rest.

Referring now to the drawings, a cross-bar or horizontal, transverse support 1 of a grinding machine supatent ice ports a slide 2, which forms the basis of the grinding attachdent and can be displaced transversely to the grinding table by means of the threaded spindle 3 which is rotatably mounted on the support 1 and extends through one or more threaded bores formed in a corresponding number of lugs or projections 3a fixed to the side of the slide 2. Thus, rotation of the spindle traverses the slide 2 across the support-1. Secured to the slide 2 are two lugs 4 in which the swivel plate 5 is supported. The swivel plate 5 is formed by the arms 5a, which are interconnected by transverse connecting members 5b and 5c, 5d, and is swivelly supported in the lugs 4 by means of the bolts 6. On the transverse connecting member 5b guides or guide tracks are provided in which a slide 7 is moved up and down. This slide 7 carries the bearing plate 9 of the grinding motor 10, which plate is likewise shiftable and adjustable relative to the slide 7 with the aid of the screw 8. The grinding motor 10 drives via the V belt 12 the V belt pulley 13 which is supported on the arbor 14. The latter is mounted in the bearing 15 and carries on its other end the grinding wheel 16. The bearing 15 is so secured to the bottom end of the slide 7 that the arbor of the grinding wheel can reach a position vertically below the axis of the swivel or pivot bolts 6 on which the swivel plate 5 is mounted. By means of the handwheel 17, arranged on the shaft 18 which is guided in the stirrup 18a, the threaded spindle 20 is turned via the pair of bevel gears 19. The spindle 20 engages the threaded nut 22 of the slide 7 so that said slide, together with the motor 10 and the grinding wheel 16 can be vertically adjusted. The spindles 18 and 20 are mounted in the cross piece or transverse member 5d. Swivelly secured to the left arm 5:: of the swivel plate 5 by means of the bolt 24 is furthermore an arm 26,'to which is attached the grinding wheel dresser constituted by the compound slide rest A and the diamond 28. As the compound rest A with the diamond 28 is in the way during grinding, it can be swivelled by means of a small motor 29 via the wire rope or cable 30 into the position indicated by broken lines in Fig. 1. To this end, one end of the rope or cable is connected to a drum 30a, while the other end is connected to a plate 30b mounted on the bolt or axle 24, whereby the plate 30b is fixedly connected to the arm 26. Upon operation of the motor 29, the cable is either wound onto or unwound from the drum 39a so as to move the arm and the dresser either to the broken line position or to the full line position, respectively, shown in Fig. 1.

The dial gauge micrometer 32 on the compound rest A serves to measure the height at which the diamond or other dressing element should be set. The compound rest A must be clamped in the grinding position by means of a locking screw 33. Mounted in the slide 2 is a spindle 34, by means of which the threaded spindle 37 is rotated via the bevel gears 35 and 36. The threaded spindle 37 engages the threaded nut 37a, which is fiexibly or resiliently articulated to the swivel plate 5, whereby the swivel pla-te 5 and thus the grinding wheel may be swung out of the vertical plane into the dotted position S and vice versa. The spindle 34 is connected via a reduction gear 38 to the motor 39 which effects the automatic feeding-in of the grinding wheel toward the workpiece 50. A hand-operated drive 40 (Fig. 2) also enables the grinding wheel 16 to be fed in and Withdrawn manually. The vertical position of the swivel plate 5 is the Zero position. Here the grinding wheel spindle axis is located in the same vertical plane as the swivel axis of the plate 5, i. e., it is located vertically below the axis of swivel 0 constituted by the bolts 6 and thus is in its lowest position. The diamond, when dressing the grinding wheel, moves in the plane E formed by the two t I V 3 axes. This plane swings'out of the zero position angle a.

The feed-in motor 39 is controlled by a switch 42, which has twocontacts 43 and 44. 'l'he switch-42 is actuated by a stop 45 which is secured on'the' swivel plate so that it moves along with the grinding wheel 16. Connected to the circuit, which is first closed by the switch 42, is a signal lamp 46 which shines red for instance, while a green lamp 47 is switched in by means of the contact 44.

7 As may be seen from Fig. l, the workpiece, 50 is clamped to the worktable 51, and arranged beside the latter is the template 52 which is vertically adjustable,

as by means of a screw 52a. Two dial gauge microm- Figs. 1 and Zillustrate a, peripheral grinding wheel 16 by means of which wheei horizontal grinding sur-' faces are machined. If profile surfaces, in which two surfaces are at right angles to each other, have to be ground, two grinding wheels arranged side by side and a compound rest with two diamonds are used.

As is shown schematically in Fig. 6, secured to the arm 26 is the compound rest A1 which is swivelly mounted on the pivot 55 and can be locked at a predetermined position. The diamonds 57 and 58 are arranged at right angles to one another and are shiftable in the already mentioned plane E. The arrows show the paths along which the diamonds 57 and 58 can be moved. When'one'of the diamonds is shifted in the direction of arrows 6i and 61, the wheel 16a will be dressed at an'angle of 45, and when the other diamond respectively, are connected via belts 63, 64, and 65' with each other and with a non-rotating screw 66 on wh ch is arranged a worm gear 67 shaped as a threaded nut. The gear 67 can be rotated via a worm 68'. The

belts move both slides 61' and 62' simultaneously in the same direction and at the same time cover the slide guides 60:: and 6% not occupied by the slides 61 and 62', respectively. V

When the compound rest A1 is rotated about the pivot 55 (or bolt 55') and locked in such a way that one of the diamond dressers, say 57 (or 57'),moves in a horzontal plane, i. e. in a direction substantially parallel to or coincident with the arrows 64 and 65, shown in Fig. 6,'

a grinding wheel can be dressed horizontally as shown in Figs. 1 and 2. A small motor 68 (Fig. 6) maybe provided for connection to the worm'68 to move the slides of the compound rest.

' The procedure is as follows:

The workpiece G is clamped to the grinding table 51. The template 51 is arranged beside the said workpiece. The heightof the template is set at the finished dimension of the. workpiece. The swivel plate 5 is brought into the zero position, ix=0. Then the diamond dresser 23 is brought, with t.e-aid' of suitable adjustment'rneans, to the template height as read on the dial micrometer 32, whereupon the grinding wheel 16. is dressed with the diamond in the manner already described. The grinding wheel is now accurately set at the template height,'i. e. at thefinished dimension of the workpiece. The grinding allowance. Z. is' determined with the aid of thetwo diai micrometers 53a and 54 and' the s w'ivel plate; is sWungoutof the vertical. plane: B through an angle a, the size of which corresponds to by the 7 the feed-in travel required to remove the grinding allowance Z. 'The grindingprocess is now carried out, the slide 2 moving horizontally past the workpiece 50. The speed of the feed-in motor and thus the time of the feed-in travel is controlled bymeans of a potentiometer (not shown). The swivel plate now moves uniformly into the zero position, while the feed-in travel of the grinding wheel is, in accordance with thesine function,- reduced to zero and the nominal dimension is attained in this position. When the swivel plate 5 has almost reached its zero position, the stop 45 closes the contact 43 so that the red lamp 46 lights up, indicating that the grinding wheel has practically completed its work. The operator now checks whether the grinding wheel needs to bedressed for the last turn. If this is so, he swivels the compound rest A into. the dressing position and trues the wheel '16,-it being possible for him to feed the grinding wheel into the diamond dresser .28 by means of the handwheel 17. Then, the compound rest A is raised onceagain and the grinding process continued until the green lamp lights up and the feed-in motor is switched ofi.

The grinding of profile rails is effected in a similar manner, except that a template, whose shape is adapted to the profile rails, is used for the setting ofthe two diamond dressers. V e

Various changes and ;,modifications maybe made without departing from the spirit and scope of the present invention and it is intended that such obvious changes and modifications be embraced by theannexed claims. I i 1 Having thus described the invention, What is claimed as new and desired to be secured by Letters Patent,- is:

' 1. In a grinding machine having a grinding wheel, means supporting said grinding wheel and arranged for pendular swingingmovement about a first axis to move said grinding wheel toward and away from a workpiece,

respectively, and dresser means for trueing said grinding wheelja first arm swingably attached at one end thereof to'said supporting means for movement a'bout a second axis, and rest means attached to the other end of said arm and carrying said dresser means, said first and second axes being disposed in said supporting means and in a common plane with the axis of rotationof said grinding wheel.

2. In a machine according to claim 1, means operative. ly connected to said first arm for, swinging. the latter disposed substantially at right angles to said first and second axes, template means arranged to be positioned adjacent said workpiece upon grinding of the latter by said grinding wheel, the height of said template means corresponding to the final dimensions to-be' imparted to said workpiece, and a pair o f dial: micrometers supported by said second arm and.operatively'engaging said template means and said workpiece, respectively,-

whereby the nominal dimension of said template means is indicated by one 'of said dial micrometers while the actual dimensions of said workpiece are indicated by the other of .said dial micrometers. J

4. In a machine 'accordingto claim 3, said onedial micrometer being; positioned. on said secondarrn at a predetermined distance from said third axis; whereby.

said one dial micrometer may be swung over said dresser meansfl f. y

.5. 'In a machine according to claim 1; said rest means comprising a triangular block, pivot means on said first arm and supporting said block for rotation about an axis substantially perpendicular to said axis of rotation of said grinding wheel, said block being provided with a peripheral guide track, and a pair of slides movably arranged in said guide track, said dresser means comprising a pair of diamonds mounted in said slides, respectively.

6. In a machine according to claim 5, two of the sides of said block being arranged at right angles to each other, said slides being arranged on said sides of said block, respectively, and belt means interconnecting said slides, whereby the latter may move jointly and in the same direction about said block during trueing operations.

7. In a machine according to claim 6, said belt means being substantially coincident with and covering those portions of said guide track not occupied by said slides.

References Cited in the file of this patent UNITED STATES PATENTS 269,915 Case Jan. 2, 1883 1,104,988 Hanson July 28, 1914 1,899,654 Ward Feb. 28, 1933 2,028,315 Bruhl Ian. 21, 1936 2,130,021 Neugart Sept. 13, 1938 2,633,674 Fouquet Apr. 7, 1953 

